By Geo on Monday, June 24, 2002 - 01:44 pm:

I dynoed my bike at 4,000 miles (pre the 4500 mile inspection) and the dyno showed like all the ones here:
At 9,000rpms it climbed up to 9,500, then droped slightly to 10,500 but stayed above the 9,000rpm level.
When I had the bike serviced at the dealer they said that the valve clearance was ok but it looked to me like he was forcing the gage pretty hard in there.
I felt that the bike was not running that hard so I had another dyno at 5,400 miles: the power tops off at 9,000 and drops down steeply from there.
Ouch!
The tuner told me that he thinks the valves were too tight. I didn't worry much because I haven't made any top speed runs in quite a while -it's been raining for 6 weeks straight!- and I usually shift up at 9k rpms anyway.
I'm at 6,300 miles now and last Sunday I'm chasing my friend on his brand new SP-2 and he leaves me standing from 80 to 130mph. I check my tach and even in 4th gear the bike is having a hard time reaching red line.
I'm thinking of going back to local butcher but I wanted to know if anyone else had a similar experience before hand.
Thanks
geo  

By Redlionfalco on Monday, June 24, 2002 - 02:08 pm:

Just a thought, have you checked your chain tension. I had the same thing on my Falco after a service which was caused by a slightly tight chain (18-20mm). Once slacked off to 25-28mm it was back to its usual self. When checking make sure you measure at 300mm intervals around the length of the chain to make sure you pick up on any tight spots.  

By Geo on Monday, June 24, 2002 - 02:29 pm:

Chain tension?
Thanks that's good to know, I'll ask them to check that too.
How many miles were on your bike when the power dropped off? I don't remember the service calling for the chain to be adjusted at 4,500 mile.
Geo  

By Redlionfalco on Monday, June 24, 2002 - 03:13 pm:

Chain adjustment is a routine service check irrespective of service interval. I check mine every few hundred miles as a worn chain can suddenly wear very quickly. But this should become part of your pre ride bike check(as well as other items as oil level, tyres lights, linkages etc.). Also if you dont regularly (150-200mls)lube your chain it'll wear out much faster than a well lubed one. Also it'll run less easily which will also soak up power. My chain is now 11k miles and still has life in it.  

By Redlionfalco on Monday, June 24, 2002 - 03:16 pm:

One other thing - Dont trust your dealer to get it right. In my experience most workshops leave the routine stuff like chain adjustment to the boy, and just how competent is he?  

By Geo on Monday, June 24, 2002 - 05:12 pm:

Oh crap this is a case of the blind leading the blind! I though you were talking of the CAM chain, not the drive chain!
Yeah I check and adjust that one myself, I have been doing it for 30 years now, the 'prilia is pretty easy on its chain for a twin, probably because of the cheater clutch and that having the Rene non-box I vent the crancase breather right on it. Messy but it's always lubricated.
But NO, the drive chain will not cause *this* problem.
Hu...thanks again.
Geo  

By Geo on Tuesday, June 25, 2002 - 12:29 pm:

So no one here had problems with valve clearances being too tight? -or loss of power just on top?
Geo  

By Crmc33 on Tuesday, June 25, 2002 - 10:53 pm:

IMHO if the valves are that tight you should be more worried about the valves burning than power loss!
I always thought that slightly tight valve clearances would give more topend power not less (as long as the valve is closing properly).
I was once told by an ex-motoxer that he set is 4 stroke up with wide tappets to give more midrange punch (higher inlet gas speed) altho I think it was just his excuse for the Honda camshaft death rattle